Progress in fabrication technologies has allowed the engineering of optical fields at subwavelength scales [1]}, [2]}, [3]}, leading to the discovery of many novel phenomena such as extraordinary optical transmission, in which an above-unity normalized-to-area transmittance is achieved by introducing a two-dimensional (2D) periodic array of subwavelength holes into a metallic film [4]}. A good understanding of these phenomena requires going beyond the traditional Kirchhoff paradigms [5]}. As proposed by Bethe in 1944, the diffraction field of a small metallic aperture can be considered as excited by magnetic and electric moments [6]}. Substantial progress in both theoretical and experimental aspects has been made since then [7]}, [8]}, [9]}, [10]}, [11]}, [12]}, [13]}, [14]}, [15]}, [16]}, but mainly focused on transmission enhancement. In this work, we demonstrate that subwavelength apertures also provide a way to engineer the reflectivity of the metal film by tailoring the retarded phases of the beam.
